Date: Thu, 03 Jul 2003 15:11:21 -0300 From: "Daniel C. Sobral" <dcs@tcoip.com.br> To: Ian Dowse <iedowse@maths.tcd.ie> Cc: freebsd-arch@freebsd.org Subject: Re: Unmounting by filesystem ID Message-ID: <3F0471C9.5080003@tcoip.com.br> In-Reply-To: <200306282254.aa83607@salmon.maths.tcd.ie> References: <200306282254.aa83607@salmon.maths.tcd.ie>
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Ian Dowse wrote:
> The patch below adds a new mount flag MNT_BYFSID that can be used
> to unmount a filesystem by specifying its filesystem ID instead of
> a path. The umount utility is changed to use this mechanism by
> default. This approach has a number of advantages:
>
> - It avoids any lookup operations that could potentially block
> forever, so filesystems such as NFS can be reliably unmounted
> even if the server is not responding but looking up the root node
> would require an RPC (maybe to an underlying filesystem).
> - The filesystem specification is unambiguous, so umount(8) can
> be sure that it is unmounting the correct filesystem (more
> work in umount(8) may be required here).
> - Detached filesystems can be unmounted. If a filesystem becomes
> detached from the filesystem hierarchy because the underlying
> filesystem got unmounted, it does not require a reboot to unmount
> it.
>
> Since unmounting by a path name is now only required for compatibility,
> in that case unmount() now just does a string comparison to find
> the correct filesystem. Also, this patch only affects unmounting;
> a similar approach could be applied to MNT_UPDATE mount operations.
>
> I would like to commit this during the next few days. Any comments
> or suggestions?
Just in the unlikely case no one has said this to your face yet, man,
you rule.
--
Daniel C. Sobral (8-DCS)
Gerencia de Operacoes
Divisao de Comunicacao de Dados
Coordenacao de Seguranca
VIVO Centro Oeste Norte
Fones: 55-61-313-7654/Cel: 55-61-9618-0904
E-mail: Daniel.Capo@tco.net.br
Daniel.Sobral@tcoip.com.br
dcs@tcoip.com.br
Outros:
dcs@newsguy.com
dcs@freebsd.org
capo@notorious.bsdconspiracy.net
One time the police stopped me for speeding. They said, "Don't you know the
speed limit is fifty-five miles an hour?" I said, "Yeah, I know, but I
wasn't
going to be out that long."
-- Steven Wright
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